A058409 Number of 4 X n nonnegative integer matrices with all column sums 3, up to row and column permutation.

1, 3, 18, 92, 458, 1982, 7928, 28592, 95138, 292993, 845027, 2295322, 5915631, 14535676, 34224682, 77510148, 169459010, 358698558, 737106306, 1473867060, 2873564862, 5472731212, 10198198452, 18621343624, 33361303957, 58713103696

Offset: 0

Author

Vladeta Jovovic, Nov 25 2000

Keywords

• easy
• nonn

Links

• Vladeta Jovovic, Number of m x l nonnegative integer matrices with all column sums equal to n, up to row and column permutation

Crossrefs

Cf. A050532, A058390, A058407, A058408, A058410.

Formula

G.f.: 1 / 24*(1 / (1 - x)^20 + 6 / (1 - x)^6 / (1 - x^2)^7 + 3 / (1 - x^2)^10 + 8 / (1 - x)^2 / (1 - x^3)^6 + 6 / (1 - x^4)^5).

Extensions

More terms from Max Alekseyev, Jun 21 2011